JPH0260521B2 - - Google Patents

Abstract

A tire having a pair of bead portions for mounting on a rim, a tread portion radially outward of said bead portions and connecting sidewalls is cast and cured from different liquid elastomer forming materials in a three-stage process. First, the inner layer of the tire is molded of high modulus material on a collapsible core in a mold with an outer shell. Second, the first outer shell is removed and a second outer shell of a second mold is mounted around the core and cast inner layer. The tread portion of the tire is then molded by centrifugal casting from a low modulus material. Third, the sidewalls are molded of low modulus, optionally microcellular, material by injection of the liquid elastomer forming material into the sidewall spaces between the molded inner layer and the second outer shell.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to cast tires of the type made by injecting or injecting liquid elastomer-forming materials into a mold, and more particularly to cast tires of the type made by injecting or injecting liquid elastomer-forming materials into a mold, and in particular by placing materials of different modulus of elasticity into the tire. , relates to tire construction and manufacturing methods that provide limited tire inflation and optimal flexibility without premature fatigue failure. Traditionally, tires have been cast from relatively high modulus materials to maintain their shape. However, during operation, repeated stresses applied at certain stress concentration points in the tire caused premature failure.

Other tires have been proposed that are comprised of multiple plies of materials of different modulus of elasticity. These tires have a relatively large number of very thin plies and are sprayed to form layers of material of different modulus on the mold surface and on the outer plies so that the plies of soft material outweigh the plies of hard material. has been made to exist between or on. High modulus plies are present in all parts of the tire, and low modulus plies are present between these plies, thus requiring a construction in which low modulus plies are present similarly in all parts of the tire. It was hot. Also, problems occurred in the distribution of the sprayed material, and in some cases shaping the plies required templates or spreaders. In other proposed tires having a tread of material of different modulus than the tire body,
The tread was formed in front of the body, which made it impossible to adjust the shape of the body and tread or to completely fill the mold.

The present invention relates to composite tire structures and methods of manufacturing tires. The high modulus inner layer on the inner surface of the tire is flexible, has low tensile strain, and resists blistering during use. A low modulus, optionally microporous, material in the sidewall is bonded to a high modulus inner layer and provides cushioning and abrasion resistance, and also defines a surface in the sidewall. A tread portion made of a material with a relatively low modulus, but higher modulus than that of the sidewalls, is applied to the crown portion to provide the necessary abrasion resistance.

According to one aspect of the invention, two spaced bead portions for attachment to a rim, one crown portion spaced radially outwardly from the bead portions; two sidewall sections extending from one said bead section to another said bead section, a strong cast inner reinforcing layer of relatively high modulus material, and an outer surface of said inner reinforcing layer having said crown section. a tire comprising a tread of a relatively low modulus material bonded at a radially outer location of the tire, the sidewall section comprising a relatively low modulus material, and a tread between the tread section and the bead section; A toroid-shaped pneumatic tire, ie an annular pneumatic tire, is provided for attachment to a rim, characterized in that the pneumatic tire is located on and adhered to the outer surface of the inner reinforcing layer.

According to another aspect of the invention, an outer ground-contacting tread section, a pair of spaced apart beads, and two individual beads extending radially inwardly from an axially outer lip of the tread section joining each bead are provided. A method is provided for manufacturing a toroid-shaped pneumatic tire comprised of sidewalls by casting and curing a liquid reaction mixture to produce an elastomeric material. The method includes the following steps: (A)(i) forming an inner reinforcing layer having a predetermined thickness less than the thickness of the tire, having an annular shaped cavity and an annular cocoa located within the cavity; providing a rigid mold defining a space; (ii) placing two beads within the space; and then injecting a liquid reaction mixture of elastomer-producing material into the space, causing the reaction mixture to react and at least partially react; curing to form a dimensionally stable inner reinforcing layer of a relatively high modulus material containing the beads;
and forming a strong cast inner reinforcing layer by taking out the core having the inner reinforcing layer on the surface; (B) forming a second mold having an annular cavity with a surface corresponding to the outer surface of the tire; prepare and process
The core having the inner reinforcing layer produced in (A) on its surface is placed in the second mold and a predetermined amount of the liquid reaction mixture of elastomer-forming material is applied to form the outer tread of the tire. introducing the reaction mixture into the space between the annular cavity of the second mold and the inner reinforcing layer, and reacting and at least partially curing the reaction mixture into a radially outer portion of the inner reinforcing layer. (C) forming a tread by a method that produces a dimensionally stable composite of the tread consisting of a relatively low modulus material overlapping and integrally bonded thereto; the sidewall space between the surface of the second mold is at least partially filled by injecting a predetermined amount of a liquid reaction mixture of elastomer-forming material, optionally containing a blowing agent; The mixture is reacted, optionally foamed and at least partially cured to fill the sidewall space, overlying and integrally bonding the inner reinforcing layer and integrally bonding the tread portion. (D) forming an outer sidewall of a relatively low modulus material, optionally microporous, of the composite bonded to; (D) finally inner reinforcement; curing the integrally assembled composite of the layer, the tread portion and the sidewall portion;
and (E) removing the formed tire and core from the mold and removing the core from the tire.

According to the above method of the invention, a high degree of adhesion between the parts of the tire is achieved and the structural retention of the inner layer to the tire is further enhanced, in this sense the inner layer is a strong cast inner reinforcing layer. It is called.

In view of the foregoing, and still in accordance with other aspects of the invention, high modulus materials are incorporated for flexibility and strength, low modulus materials are included for cushioning and abrasion resistance, A composite tire structure is then provided in which a low modulus, optionally microporous, material is included for wear resistance and surface definition.

According to another aspect of the invention, a tire construction is provided in which one layer of the tire is comprised of a high modulus material and the remainder of the tire is comprised of a low modulus material.

Yet another aspect provides a tire structure in which the tire is formed by casting and curing a liquid polymer in separate sections.

According to yet another aspect, a method of manufacturing a cast tire is provided in which portions of different modulus are separately injected or injected into a mold.

According to another aspect, a method is provided for injecting or injecting different layers of material into a mold using different mold parts.

According to yet another aspect, a method is provided in which materials of different moduli are derived from liquid polymers.

To achieve the foregoing and related purposes,
The invention is described in detail below, and with particular reference to the claims, the following description, and illustrative embodiments of the invention, which embodiments represent only one of various methods in accordance with the principles of the invention. It consists of the features pointed out in the accompanying drawings. The invention will be further explained with reference to the drawings.

Referring to FIG. 1, there is shown a cross section of a generally toroidal shaped pneumatic tire 10 made in accordance with the present invention, the tire 10 having a bead portion 11 containing annular beads 13 and 14 of wire or relatively inextensible material. and 12. Bead portions 11 and 12 are adapted for attachment to a vehicle rim (not shown) rotatable about an axis. "Pneumatic tire" means a tire having an air chamber therein that may be pressurized or unpressurized during use. Thus, it encompasses pneumatic tires that rely on internal air pressure for support and semi-pneumatic tires that do not necessarily rely entirely on indoor air pressure for support during use.

Radially outwardly of the bead portions 11 and 12 there is a tread portion 15 which has the shape of a tread on its radially outer surface comprising ribs 16 separated by grooves 17. On the radially inner surface of the tire 10, an inner reinforcing layer 18 connects the beads 11 and 12. Sidewall section 18 has a thickness T-1, which is approximately one-third the thickness of the tire wall at the tread section 15, and a tread section thickness T-T. It is about two-thirds of the thickness T of . In the embodiment shown, the tire 1 at the tread portion 15
0 wall thickness T is three-quarters of an inch (1.91 cm), inner layer 18 thickness T-1 is one-quarter inch (0.64 cm), and tread thickness T-1.
T is 1/2 inch (1.27 cm). This is for relatively small tires, and their thickness may vary substantially for other tire applications. In fact, the present invention
It is particularly suitable for tires with a tread thickness of cm) or more, in which case curing takes much time with other materials, but only in a very short time with the material of the invention.

On the side of the tire 10, radially outwardly of the inner layer 18, there are side walls 19 and 20 extending from the beads 11 and 12 to the tread 15.
Preferably, the tread portion 15 extends across the crown portion 23 of the tire 10. Crown part 2
3 can be defined as the part of the tire extending from position A on one sidewall to position B on the other sidewall, positions A and B are located at a distance CH from the base Z of the tire, and this distance CH cross-sectional height of
Not less than three quarters of SH.

The apparatus for forming tire 10 is shown in FIGS. 2-5. FIG. 2 shows a rigid mold 24, which can be adapted for centrifugal casting, and which has a segmented collapsible core 25, for example bolts and nuts 29. Flange 2 with fasteners
The clamp ring 28 fastened to the shaft 2
It is rotatably attached to the flange 26 of 7.

The shaft 2 is held together by a clamp ring 35 and is rotatable with the collapsible core 25.
two mold parts 33 and 34 attached to 7
The outer shell 32 containing the collapsible core 25 is disposed around the collapsible core 25. A cavity 38 is formed between the outer surface 36 of the core 25 and the inner molded surface 37 of the outer shell 32 for receiving a liquid reactive elastomeric material to form the inner layer 18 of the tire 10 . Beads 13 and 14 are spacers 3
9 and 40, and the annular flange 41 is positioned proximate a spacer on the inner molding surface in spaced relation to the outer surface 36 of the core 25 to provide an inlet near the bead 113. An outlet opening 43 is formed near opening 42 and opposite bead 14 . The liquid reactive elastomeric material is injected through the inlet opening 42 and the mold is vented through the outlet opening 43. The flange 41 on the inner molding surface is attached to the bead 11 of the tire.
and 12 rim engaging surfaces. The inner layer 18 shown in FIG. 1 is formed by a suitable molding method.
For example, they can be made by injection molding or centrifugal molding a liquid reaction mixture and curing it to form a suitable polyurethane composition having a hardness of about 90 Shore A to 50 Shore D. Such polyurethanes can be prepared, for example, by methods well known to those skilled in the art, such as (A) a polymeric polyol, e.g., a molecular weight of about 700 to about 10,000 and a
(B) a slight stoichiometric excess of an organic polyisocyanate having an average isocyanate (NCO) functionality ranging from about 2 to 2.3; and (C) a chain extender or curing agent of a diamine or a monomeric polyol containing an average of 2 to 2.3 hydroxyl groups and reacting the same. Generally, polyurethanes can be formed by any of the well-known prepolymer, quasi-prepolymer or one shot processes. Prepolymer or quashi prepolymer methods are generally preferred, in which the reaction products of (A) and (B) are mixed with a curing agent (C) to form a reaction mixture.

Inner layer 18 preferably has a modulus in the range of about 900 to 2500 ^psi at 100% elongation ^;
7250psi) range of Young's modulus, approximately 281.2~562.4Kg/
It is important to consist of a high modulus material having an ultimate tensile strength in the range of about 4000 to 8000 psi and a tensile strain in the range of 0 to 10% at 100% elongation ^, preferably less than 3%. What is “tensile strain”?
It refers to the residual elongation expressed as a percentage of the original length when a sample is stretched and contracted in a specified manner. Inner layer 18 after injection into cavity 38
is maintained at an elevated temperature of about 250° C. (121° C.) for several minutes to several hours to at least partially cure the layer. The outer shell 32 is then removed by removing the clamp ring 35 and the mold parts 33 and 34 are attached to the core 2.
5 can be pulled away from the inner layer 18 supported on it.

Referring to FIG. 3, inner layer 18 containing core 25 and beads 13 and 14 is placed in a second mold 44 having mold sections 45 and 46 held together by clamp ring 47. Referring to FIG. Suitable heating means (not shown) are provided to heat mold sections 45 and 46 during the molding operation. Mold portions 45 and 46 support shaft 27 for rotation about its axis. Mold openings 48 and 49 in mold sections 45 and 46 define mold cavities 5 defined by inner layer 18 and radially inner surfaces 53 of the mold sections.
Provide an entrance/exit to 2.

Referring to FIG. 3, the tread portion 15 of the tire 10 is shown to be formed by centrifugal casting or injection molding. The tread portion 15 is a low modulus tread mixture of elastomeric material;
For example, the inner layer is of the type mentioned above, but at 100% elongation it is approximately 28.1 to 105.5 Kg/
modulus in the range of cm ² (approx. 400-1500psi), approx.
Young's modulus ranging from 52.7 to 101.9 Kg/cm ² (about 750 to 1450 psi), about 105.5 to 492.1 Kg/cm ² (about 1500 to 7000 psi)
made from a suitable polyurethane having an ultimate tensile strength in the range of , an ultimate elongation in the range of about 500-1000%, a compressive strain of less than 25%, and a glass transition temperature (Tg) of less than -30°C. By injecting a certain amount of tread material into the mold cavity 52, only the radially outer part is filled during centrifugal casting;
A tread portion 15 is formed. This portion 15 is adhered to the inner layer 18 and has a tread shape with grooves 17 formed in the tread surface by ribs 54.

The tread portion 15 is partially cured in mold 44 at a controlled temperature and then as shown in FIGS.
The illustrated sidewalls 19 and 20 are formed by injecting a predetermined amount of a liquid reactive elastomer-forming material, such as a polyurethane precursor, into the sidewall spaces 55 and 56 of the mold cavity 52. The side wall spaces 55 and 56 form the mold portion 45
and radially inner surface 53 of 46, inner layer 1
8 and the radially inner surface of the tread portion 15. The side wall spaces 55 and 56 are partially filled with polyurethane having a low modulus and optionally a microporous structure. This microporous structure may contain a well-known inert fluid blowing agent in the mixture of Quashie prepolymer and curing agent to control the reaction mixture injected into spaces 55 and 56 during curing. It is obtained by foaming. Blowing agents can be used in varying amounts depending on the desired structure. Typical blowing agents are air, water (to generate carbon dioxide when reacting with the polyurethane precursor),
nitrogen, carbon dioxide, and halogenated hydrocarbons,
For example, methylene chloride, trichloromonofluoromethane, dichlorodifluoromethane and 1,
2-dichlorotetrafluoroethane. Also useful are heat activated blowing agents such as nitroso compounds which liberate nitrogen gas upon decomposition. The microporous structure has a specific gravity of the polyurethane base material of approximately 5 to 20.
%, preferably about 5-10%.

The unfoamed polymer of the base material of sidewalls 19 and 20 has a modulus in the range of about 400 to 3000 psi ^, and a modulus in the range of about 725 to 351.5 Kg/ ^cm2.
5000psi) range of Young's modulus, approximately 105.5~492.1Kg/
It has an ultimate tensile strength in ^the range of about 1500 to 7000 psi and a glass transition temperature (Tg) of -30°C or less.

By using a microporous material for sidewalls 19 and 20, the sidewall pattern is filled as the reaction mixture expands during molding, and especially when the formed product tends to shrink during molding. ,
By counteracting or reducing such tendencies, the desired surface clarity is provided.

Sidewalls 19 and 20 and inner layer 18 and tread portion 15 are then placed in mold 44 for tire 10.
Hold these parts long enough to cure. Examples of curing times and temperatures in the mold for suitable tires 10 are from about 60°C (150°C) to about 177°C.
It takes several minutes to several hours at a temperature of (350〓). After curing the tire 10 in the second mold 44, the clamp ring 47 is removed to allow mold portions 45 and 46 to be removed from the tire. The collapsible core 25 and the tire 10 molded thereon, shown in more detail in FIG. 5, are separated from the flange 26 by removing the nuts and bolts 29 and removing the clamp ring 28 from the core. .

Core 25 is segmented as shown in FIG. 5, with key segments 57 and other segments 58 spaced about the circumference of the core. By first removing key segment 57, other segments 58 can be removed from the tire. The core 25 can then be reassembled onto the flange 26 and the mold 24 placed around the core to mold the other inner layer 18.

After removing the tire 10 from the mold 44 and placing it in a heated curing chamber (not shown), it is desirable to fully cure it. In that case, the shape of the mold includes mold parts 45 and 46 and core 25.
is of such a shape that it can be removed without damaging the tire. The tire 10 is then placed in a curing chamber at substantially the same curing temperature for several minutes to several hours until the tire is fully cured. Next, tire 1
0 is removed from the curing chamber and cooled to room temperature.

In the description of the invention, polyurethane has been described, which is in fact preferred. The chemistry of such polyurethanes is generally known to those skilled in the art. Generally, the polyurethane precursor is provided as a liquid reaction mixture that is poured into a mold and cured. The liquid reaction mixture is generally of a conventional prepolymer process, a quasie prepolymer process, or a one shot process. The components of polyurethanes are common polymeric polyols, polyisocyanates and diamines or monomeric polyols, usually diol hardeners. Small amounts of organic solvents are used as carriers, if necessary. However, for the present invention, it is preferable not to use a solvent at all. The polymer polyol typically has a molecular weight of about 700 to about
It is a polyester or polyether polyol with a molecular weight in the range of 10,000.

In the practice of this invention, the polymeric polyol preferably has a hydroxyl functionality of about 2 to enhance the elastomeric properties of the polyurethane.
The polyurethane is prepared with a slight excess of isocyanate so that the diamine or diol, preferably the diamine curing agent, can react therewith to effect the necessary crosslinking or extension.

Above, the tire and its manufacturing method according to the present invention have been explained in detail with reference to the drawings.
In the tire of the present invention, the inner reinforcing layer is comprised of a high modulus material having a high modulus of elasticity and a high Young's modulus in a specific range, thus giving the tire flexibility and low strain properties and making it bulge resistant. while the tread portion integrally bonded to the inner reinforcing layer is comprised of a low modulus material having a specific range of low elastic modulus and low Young's modulus, thus imparting dimensional stability and wear resistance to the tread portion; Similarly, the side wall portion, which is integrally bonded to the inner reinforcing layer, is made of a low modulus material having a low elastic modulus and a low Young's modulus within a specific range, thus making the side wall portion wear resistant and providing optimum cushioning properties for the tire. Provides shock absorption properties. Since the tire of the present invention is thus constructed of an inner reinforcing layer of a high modulus material having a specific modulus of elasticity and Young's modulus, and a tread portion and a sidewall portion of a low modulus material each having a specific modulus of elasticity and Young's modulus, In addition, the entire outer surface of the tire is wear resistant, giving the tire a high degree of early fatigue failure resistance, excellent blistering resistance, and optimal cushioning.

On the other hand, according to the method of the present invention, the inner reinforcing layer, the tread portion, and the side wall portion are all formed by casting the elastomer-forming reaction mixture.
The adhesion between the inner reinforcing layer, the tread portion and the sidewall portion is extremely strong, making it possible to easily produce a composite tire of the above configuration with excellent structural integrity. Furthermore, according to the method of the present invention,
Unlike conventional tire manufacturing methods, where a large number of plies of materials with different modulus are formed and layered by a spraying method, the troublesome operations of conventional tire manufacturing methods eliminate the problem of uneven distribution of the sprayed material, and the treads are formed separately. It is possible to easily manufacture a tire in which each part of the tire is made of a material with a different modulus, without the difficulty of controlling the shape or alignment of the other method of joining the tire body made of a material with a different modulus.

Although certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. .

[Brief explanation of the drawing]

1 is a cross-sectional view of a tire manufactured according to the present invention; FIG. 2 is a schematic cross-sectional view of a mold and collapsible core for casting the inner layer of the tire shown in FIG. 1; 3 is a cross-sectional view similar to FIG. 2 of a tire mold having a second mold and an outer shell for casting the tread of a tire by centrifugal casting or injection molding, and FIG. 4 is a cross-sectional view similar to FIG. Figure 5 is a diagram similar to Figure 3 showing a note of
FIG. 2 is a schematic side view showing a segmented collapsible core. A, B...position of crown part, T...thickness of tire wall at tread part, T-1...thickness of inner reinforcing layer, Z...tire base, T-T...thickness of tretz part, CH...tire base Distance from to the crown part, SH...Tire section height, 10...Troid-shaped pneumatic tire, 11, 12...Bead part, 13, 1
4... Annular bead, 15... Tread portion, 18... Inner reinforcing layer, 19, 20... Side wall portion, 23... Crown portion, 24... Rigid type, 25... Collapsible core, 2
6... Flange, 28, 35, 47... Clamp ring, 32... Outer shell, 33, 34, 45, 46... Mold part, 36... Outer surface, 37... Inner molding surface, 38,
52...Cavity, 39,40...Spacer, 4
1... Annular flange, 42, 43, 48, 49... Opening, 44... Second mold, 53... Radial inner surface, 5
5... Rib, 55, 56... Side wall space, 57... Key segment, 58... Segment.

Claims (1)

Claims: 1. two spaced apart bead portions for attachment to a rim; one tread portion spaced radially outwardly from both bead portions, extending from each of the bead portions to the tread portion; a tire consisting of two sidewalls; and a strong cast inner reinforcing layer extending from one said bead to the other said bead, said inner reinforcing layer having a strength of 63.3 to 175.6 Kg/cm ² (900 to
2500psi) range at 100% elongation and
comprising a high modulus material having a Young's modulus in the range of 101.9 to 509.7 Kg/cm ² (1450 to 7250 psi); Glued and 28.1~105.5Kg/ ^cm2 (400~1500psi)
Elastic modulus at 100% elongation in the range of and 52.7~
comprising a low modulus material having a Young's modulus in the range of 101.9 Kg/cm ² (750-1450 psi); and the sidewall portion is located between the tread portion and the bead portion and the outer surface of the inner reinforcing layer. and 21.1~105.5Kg/ ^cm2 (300~1500psi)
Elastic modulus at 100% elongation in the range of 51.0~
A toroid-shaped pneumatic tire for mounting on a rim, characterized in that it is made of a low modulus material having a Young's modulus in the range of 351.5 Kg/cm ² (725-5000 psi). 2. The toroidal pneumatic tire of claim 1, wherein the low modulus material of the sidewall is microporous. 3 The inner reinforcing layer is 90 shore A to 60 shore D.
of hardness, an ultimate tensile strength in the range of 281.2 to 562.4 Kg/ ^cm2 (4000 to 8000 psi), and a tensile strain in the range of 0 to 10%; ² (1500~
Ultimate tensile strength in the range of 7000psi), ultimate elongation in the range of 500-1000%, compressive strain less than 25% and -30℃
consisting of a polyurethane composition having a glass transition temperature of ^cm2 (1500~
7000 psi) and a glass transition temperature below -30°C. 4 Consisting of an outer ground contacting tread portion, a pair of spaced apart bead portions, and two individual sidewall portions extending radially inward from the axially outer edge of the tread portion and joining the beads of the respective bead portions. (A)(i) a toroidal-shaped pneumatic tire manufactured by casting and curing a liquid reaction mixture to produce an elastomeric material, comprising: (ii) providing a rigid mold having an annular core positioned within the cavity to define an inner reinforcing space having a thickness determined; (ii) placing two beads within the space; and then injecting a liquid reaction mixture of elastomer-forming material into the space and reacting and at least ^partially curing the reaction mixture to contain the beads at 900-2500 psi.
Elastic modulus at 100% elongation in the range of 101.9
Forming a dimensionally stable strong cast inner reinforcing layer of a high modulus material with a Young's modulus in the range of ~509.7 Kg/ ^cm2 (1450-7250 psi), and forming the core with the inner reinforcing layer on the surface. (B) preparing a second mold having an annular cavity with a surface corresponding to the outer surface of the tire;
The core having the inner reinforcing layer produced in (A) on its surface is placed in the second mold and a predetermined amount of the liquid reaction mixture of elastomer-forming material is applied to form the outer tread of the tire. introducing the reaction mixture into the space between the annular cavity of the second mold and the inner reinforcing layer, and reacting and at least partially curing the reaction mixture into a radially outer portion of the inner reinforcing layer. 28.1~105.5Kg/cm ² (400~
producing a dimensionally stable composite of the tread portion consisting of a low modulus material having a modulus at 100% elongation in ^the range of 1500 psi) and a Young's modulus in the range of 750 to 1450 psi; forming a tread by a method; (C) injecting a predetermined amount of a liquid reaction mixture of elastomer-forming material into a sidewall space between a surface of the inner reinforcing layer and a surface of the second mold; , filled and reacted and at least partially cured with the reaction mixture overlying and integrally adhering to the inner reinforcing layer and integrally joining the tread portion. Kg/ ^cm2
(300-1500 psi) and a Young's modulus in the range 51.0-351.5 Kg/ ^cm2 (725-5000 psi). (D) finally curing the integrally assembled composite of the inner reinforcing layer, the tread and the sidewall; and (E) curing the formed tire and core. and removing the core from the tire.